package com.wiretap.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.wiretap.util.Constants;

/**
 * Servlet implementation class AuthImageServlet
 */
public class AuthImageServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	// 设置图形验证码中字符串的字体和大小
	private Font font = new Font("Arial Black", Font.PLAIN, 16);
	// A-Z,a-z,1-9
	private static final String[] base = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "1", "2", "3", "4", "5", "6", "7", "8", "9" };

	private static int validatacodeNum = 4;

	// 生成随机颜色
	Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255) {
			fc = 255;
		}
		if (bc > 255) {
			bc = 255;
		}
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}

	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//  
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "No-cache");
		response.setDateHeader("Expires", 0);
		response.setContentType("image/jpeg");

		// 指定图形验证码图片的大小
		int width = 75, height = 20;
		// 生成一张新图片
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		// 在图片中绘制内容
		Graphics g = image.getGraphics();
		Random random = new Random();
		g.setColor(getRandColor(200, 250));
		g.fillRect(1, 1, width - 1, height - 1);
		g.setColor(new Color(102, 102, 102));
		g.drawRect(0, 0, width - 1, height - 1);

		g.setFont(font);

		// 随机生成线条
		g.setColor(getRandColor(160, 200));
		for (int i = 0; i < 155; i++) {
			int x1 = random.nextInt(6) + 1;
			int y1 = random.nextInt(12) + 1;
			int x2 = random.nextInt(width - 1);
			int y2 = random.nextInt(width - 1);
			g.drawLine(x1, y1, x1 + x2, y1 + y2);
		}
		// 随机生成线条
		for (int i = 0; i < 70; i++) {
			int x1 = random.nextInt(6) + 1;
			int y1 = random.nextInt(12) + 1;
			int x2 = random.nextInt(width - 1);
			int y2 = random.nextInt(width - 1);
			g.drawLine(x1, y1, x1 - x2, y1 - y2);
		}
		// 该变量用于保存系统生成的随机字符串
		String randStr = "";
		for (int i = 0; i < validatacodeNum; i++) {
			// 获得一个随机字符
			String tmp = getRandChar();
			randStr += tmp;
			// 将系统生成的随机字符添加到图形验证码上
			g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			g.drawString(tmp, 15 * i + 10, 15);
		}
		HttpSession session = request.getSession(true);
		// 将系统生成的图形验证码放到Session中
		session.setAttribute(Constants.VALIDATE_CODE, randStr);
		g.dispose();
		// 输出图形验证码
		ImageIO.write(image, "JPEG", response.getOutputStream());

	}

	// 生成随机字符
	private String getRandChar() {
		Random random = new Random();
		return base[random.nextInt(base.length)];
	}
}
